More of the resin is trapped in the trichome caps. Youāre smelling it more because itās evaporating more, because itās not in the caps as much. You start with 100% and some % evaporates, which you can smell. When I say āalmost scentlessā I mean āan open jar will stink up the house in 5 minutesā but still be dull compared to a fresh grind. I can take that same harvest and dry some of it under a light in the veg tent and it will S.T.I.N.K. perfectly, because every last cap is wrinkled and has leaked all resin. Itās all very good fresh regardless of whether or not the caps are intact to be fair.
From what I have seen myself, a low VPD (7-10 day) dry bud that is lightly handled will look like itās covered with satin marbles under the scope. A fast dry will look like crinkled wrinkly balls of wax.
You can achieve good results by hinging around humidity as the control, taking temps as they may be, and not exceeding around 0.7 kPa VPD. You need a controlled air volume to mix before introducing slowly to the dry area and so need a big box, ultrasonic mister / dehumidifier (depending on your situation), MERV-13 filter, and a way to circulate air.
A 10-11 day dry equates to a very reasonable VPD across the dry-down and results in the best bud for me personally. Iām back calculating this based on empirical data from a bunch of drys where I weighed the sample many times each day while recording temp and humidity. I tried out various approaches and found that VPD is a predictive measure of dry time. I see VPD as a speed limit. Of course there are so so many variables from initial bud size, density, packing factor inside the unit, on and on. In general though I think (personally) that my method here preserves the maximum terps within trichome heads while still being reasonable to control and operate, has low/no mold concerns, and is fun.
Edit: Shout out to @FieldEffect for all the knowledge and info sharing, his threads have inspired me a great deal so check him out when you have a chance!
The dry machine I keep calling the V2 is the best, just manual controls at the moment.
Iām tinkering with a peltier unit array to see if I can get an appreciable temp difference between the tent and ambient. Iām using the 100% return air system (updraft) where if humidity goes high we exhaust some and pull fresh air, if satisfied we recirc air in that range and hunt VPD w/ like a literal throttle-body in the fridge/peltier loop, and a constant air 12V high-static fan. I keep getting stuck on a peltier unit to offer a 1:1 Ca***rol DIY option. That will work for sure if I throw a lot of peltier at it but costs (power supply and all the trimmings heat sinks custom housings) become that of a college/beer fridge (not really, but close) which I could just cut an intake/exhaust into and 3D print some collars, glue/great stuff them in and throttle the air supply through that to hunt some lower temp that satisfies the VPD requirement (I assume some crude PID sneaks in there over time) compared to whatever the horizontal plane of humidity happens to be based on bud envelope + low flow recirculated air (sensors mounted center-bud [not inside the bud, like center of bud in terms of not too far up or downstream of the bud itself] on each side of the chamber)ā¦
Out of curiosity how are you handling water activity with the constant VPD method? My assumption based on what you just wrote is that you are lowering the temp to find the point where the two intersect - and you wind up with an RH where you want it and get the lower VP differential via a lower temperature.
I believe the commercial machine uses a condenser coil as the dehumidifier, and thatās really all thatās in it. If you were to say, cool a radiator to what you want your dewpoint to beā¦well, all the excess water collects until the air around it has a dew point equal to that temperature. That would be lower than your chamber temperature unless you are 100% RH. Itās super easy to heat the air (resistive heating) to get whatever temp you want, and humidity is regulated using a fixed temp ādehumidifierā heatsink at the setpoint dewpoint temperature. Get my drift? Thatās just one approach that comes to mind. I think the path to stability (in both temperature and water regulation) is to keep it closed and eliminate the concept of exhausting.
And I am at the point with my contraption, even doing fixed RH with a 20 gallon igloo cooler to moderate the temp around 60F average where Iām convinced now I need to improve my growing and plant selection to get better end product. So Iām focusing on that for a while, then Iāll revisit my dry machine in a refrigerator reconfigured like I described in the preceding paragraph.
I owe you a good response on this but I keep one thing in mind, my top criteria for a functional dry tent is that I can open and close it 20x per day and still pull great bud from it 10-11 days after it goes in. One where I can add more material 4 days into a dry as I pull bud over the course of one or more weeks and it all comes out predictably groovy.
I agree the path to stability is *insulation, peltier dehu, electric reheat, wet sponge in unit and mostly, no disturbances. The V2 aims to bathe the dry area in pre-conditioned air such that the mixing at bud surface is resulting in a chosen VPD.
What do you mean by handle, I guess is the question? Iām thinking of water activity as being the stabilized headspace RH in a sealed jar. I need more data, but you probably remember those few runs where I measured weight loss (moisture content start-finish) to measured water activity (take that known moisture content loss sample and seal it up for a few days). Iām looking for 80% weight loss to start measuring water activity.
I donāt know if thereās anything you can glean from this image, but itās interesting to think about manipulating that slope and what that might change.
Before I start typing this, I really have no intent of derailing this thread, and am happy to continue this discussion wherever. It just came up, and I like yakkinā
That is beautiful data and looks much the same as mine probably does. What I meant was, what is the end-point RH (weāll assume this is equivilent to water activity after a certain point)? Like we discussed a year ago I think, seeking low vapor pressure differential at high temperature results in high water activity. I was nearly in an identical place ~63-64F and similar RH for a VPD of 0.7ish. I got away with this because things had trim time and are stored in grove bags with some level of moisture permeability. But I took more care this year to be sitting at 60% for a few days to be ādoneā before the trim/store process, which is much faster this year with my bowl trimmer. Then straight into Grove bags. Not a critique of any kind, was just curious if you had yet adopted a two-phase (dry constant VPD, ācureā constant RH) system yet.
I feel ya here. I do the same with my outdoor. And things spike for several hours after I add material. I guess Iāve just grown less concerned with that since I intend to leave things in there until they are ready and have no timeline. But Iāve found it doesnāt impact things as much as I expected. Iām using a similar exhaust system without preconditioning.
At the end of the day Iām not sure stability matters that much. I donāt think Iāve seen a single picture of the commercial device where either of the parameters actually match the setpoints. Who knows. Iām just less worried about pretty much everything after spending quite a bit of time obsessed with it, other than the end-state conditions being reasonable. Hereās an example clipped from an image I found on google, first one I could find not from the manufacturer:
Itās possible that this image has a setting of 60.5F DP but I doubt it. Itās doing its best and canāt keep up. Apparently, like we both know, until you get somewhat dry exhausting or a ridiculous dehum is the only answer. The one I want to try is the ridiculous dehum.
I do like your concept of pre-conditioning air, and recirculating once the bulk of the high-humidity air is dealt with. I think the preconditioning of the air volume is novel. When you are a few days after loading it there is only ocassionally a few seconds of exhausting at low speed, and after a week the stability is quite high functioning basically as a sealed box, which is what I/we were talking about. Neat! Iām quite curious how you will find your results and I appreciate the fact that you are taking this even further than I was willing to
Itāll be at least a year before I start on my mark 2. Hopefully you share your results and I can use it to guide my own re-investigations. Cheers buddy!
Thanks, yeah no worries Iād love to chat about this here!
Ah gotcha. And first maybe this is a factor Iām leaving outā¦ Iām drying and storing in the same space, and so the tent temperature = storage temp. Thatās the way the V2 is setup now anyways; V3 would be a cooling solution.
I can set RH to 58% within the precondition chamber and provide that to the dry chamber, and watch for the weight loss to bottom out (i.e. to be around 20% of starting weight). That would indicate itās achieved a nearly steady-state water activity level of around 60% and can go in the jar from there for burping. And since weāre at the same temp we donāt have to have back-adjusted RH to result in the right water activity once in the storage environment.
I think that all makes sense in my mind anyways! Thanks and Iāll keep you posted of any milestones met.
Iāll echo that and add not to bloom until itās past done either, as terpenes are lost and degrade after senescence. Need to find that sweet zone. I see some people obsessed with amber resin to the point that their beautiful harvest is ruined and left way too long and imo all weed at this late stage has a boring flatline buzz with poor flavor, though it can be good for sleeping. I usually toss my late buds that are left on seed branches.
Some amber, ok, but not all amber
So there is a study out that suggests that trichome color is only a reliable indicator on a strain by strain basis. This means if youāve run the same strain for a while you can feel more comfortable using teichome color. If you are looking for peak THC there are studies that say cannabinoids peak as early as week 6, but then you sacrifice yield and that is also on a strain by strain (or seed by seed) basis.
The one thing that has been consistent across trichome morphology studies is the elongation of the stalk. Trichome stalks that begin to topple over are likely the most ripe with the greatest diversity of cannabinoids, terpenes, etc. Because there is nothing conclusive, I generally take a holistic approach when growing something new and look at bracts, pistols, trichome color, trichome head size, and trichome stalk length. I donāt grow to sell so I like to let them go until they are almost bursting and full of flavor
Even if itās some amateur takes itās a good result. A feast for my eyes
